As a method of connecting a metal electrode on a surface of a semiconductor element and metal wiring such as a wire, there is a method of bonding metal wiring using an ultrasonic bonding method.
For example, Patent Literature 1 discloses an ultrasonic bonding method of vibrating a metal wire at a predetermined ultrasonic frequency while a predetermined load is applied using a dedicated jig in a state where a metal electrode on a surface of a semiconductor element and an end portion of the metal wire are in contact with each other. This is to generate local frictional heat in the contacting part in a short time and to melt the metals to be bonded together. The other end of the metal wire is similarly bonded to another electrode or the like included in a structure in which the semiconductor element is mounted.